Eur. Phys. J. B 51, 101-110 (2006)
https://doi.org/10.1140/epjb/e2006-00195-8

Phase diagrams of Ising fluids with Yukawa-Lennard-Jones interactions from an integral equation approach

¹ Institute for Condensed Matter Physics, 1 Svientsitskii Street, UA-79011 Lviv, Ukraine
² Institute for Theoretical Physics, Linz University, A-4040 Linz, Austria

Corresponding author: ^a wolfgang.fenz@jku.at

Received: 21 December 2005
Revised: 7 March 2006
Published online: 31 May 2006

Abstract

An integral equation approach is developed to investigate phase coexistence properties of Ising spin fluids with Yukawa ferromagnetic and Lennard-Jones nonmagnetic interactions in the presence of an external field. The calculations are carried out on the basis of the Duh and Henderson closure with a specific Duh-like partitioning of the total potential. The coupled set of the Ornstein-Zernike equation, the closure relation and the external field constraint are solved using an efficient numerical algorithm. The phase diagrams are evaluated in a wide range of varying the external field and the ratio of strengths of Yukawa to Lennard-Jones interactions. Different types of the phase diagram topology as well as various external field dependencies of critical temperatures and densities are identified. The complexity with respect to simple Lennard-Jones fluids is explained by coupling between spatial and spin degrees of freedom in the system. A comparison of the obtained theoretical results with simulation data is made and a good agreement is observed.